Electromagnetic device



May 13, 1958 A. R. BRINKRUFF ET AL ELECTROMAGNETIC DEVICE:

Filed June 21. 1955 Mdmamn United States Patent O ELECTROMAGNETIC DEVICE Arthur R. Brinkruif and George A. Binder, Logansport, Ind., assignors to Essex Wire Corporation Application June 21, 1955, Serial No; 516,857

3 Claims. (Cl. S17- 171) This invention is related to electromagnetic devices.

Electromagnetic devices, as for example, relays, are frequently used in applications where they are subjected to shock and vibration. In such cases malfunctioning of the relay may occur in that when de-energized unintended contact movement may occur. When the relay is energized, the relay armature is held tightly against the corepiece and does not move when subjected to vibration. However, when the relay armature is free to move, as on de-energization of the relay coil, vibration or shock may bounce the armature with a consequent and unintended movement of the armature.

The object of this invention is to provide means for restraining an electromagnetic armature to avoid accidental movement of the armature due to the effect of forces external of the device.

In the drawings:

Fig. 1 is a side elevation of an electromagnetic device in the direction of 1-1.

Fig. 2 is an end elevation of an electromagnetic device in the direction of 2 2.

Fig. 3 is an exploded projection of the header assembly of the device illustrated in Fig. l.

Fig. 4 is a side elevation of an armature.

Fig. 5 is a top elevation of the armature of Fig. 4.

The electromagnetic device of Fig. 1 is commonly described as a hermetically sealed telephone type relay. The relay consists broadly of the protective can 11, terminal header 1,2, switch stack assembly 13, armature 14, and relay coil with core piece 16.

The header 12 consists of a glass center section 17 through which the terminals 18 pass. The terminals 18 provide for external electrical connection of the relay and extend a sufficient distance through the glass center section to permit internal connection to the leads 19 extending to the various switches and to the relay coil. The glass insulating center section is held by the rim 20 and the flange 21. The entire header assembly is seated in seat 21a of the plate 22. The plate in turn seats on the shoulder 23 of the can 11 and is retained thereon by crimping over the edge 24 of the can 11. Sealing of the can is completed by soldering the fillet joint between the header rim 20 and plate 22, and the lap joint between can edge 24 and the plate 22.

The studs 25 complete the external structure of the relay and are used for mounting the relay. The studs are threaded at the one end for mounting purposes with a straight shank portion at the other for staking the studs to the retainer plate 22.

The relay coil and attachments are secured by means of an extension 26 of the core 16 which passes through the heel piece 27 and is staked thereto. The heel piece is in turn aflixed to the can 11 by means of round head screws which pass through the can and thread into the tapped holes 28 of the heel piece 27.

The stack assembly 13 consists of insulators 29 separating the contact carrying springs namely, the armature ,springs 31 and 34, break springs 30 and 33, and make 2,834,925 Patented May 13, 1,958

ICC

springs 32 and 35. The entire assembly including a re-y tainer plate 36 (to beV hereinafter discussed)l and clamp plate 37 is bolted to the heel piece in an insulating man- The springs are as.

ner as is well understood in the art. indicated individually connected toelectrical leads to the external relay connections. TheL stack assembly contains two identical stacks (Fig. 2) in order to double. the useful switching.

Switching engagement is providedy by the action ofr the armature 14 andassociated ceramic bushings 39 and 40. When the relay coil 15 isenergized the clapper portion 41 of the relay armature is attracted to the core piece 16. The armature pivots on the corner 42 of the heel piece 27 which is in engagement with the inner portion of the corner formed by the armature hook 43. The armature is held in engagement with the corner 42 of the heel piece by the restraining plate 36 which contains a rectangular opening 44 to admit the extension 45 of the armature clapper. The restraining plate as indicated above is held rigid by the switch stack screws which pass through the holes 46 and into the heel piece.

As viewed in Fig. l attraction `of the armature to the core piece will cause the armature arm 47 to move upwardly so that bushing 39 moves armature spring 31 which in turn moves bushing 40 and armature lspring 34 to which bushing 40 is mounted. Make spring 32 yand break springs 30 and 33 are recessed to permit the free travel of the bushings 39 and 40.

To avoid unintentional armature bounce and resultant contact 4break and make, magnet 48 is mounted adjacent the armature clapper 41. In the case of the unenergzed relay as illustrated, the permanent magnet tends to hold the armature open when the relay is subjected to outside forces. This magnetic restraint has both a dynamic and static characteristic.

Ordinarily, devices (such as anti-vibration springs) which are used to restrain undesirable movement of the armature 14, suter themselves from mechanical resonances. One of the advantages of the use of a permanent magnet 48 as illustrated is that it is a mechanically non-resonant device whose forces on the armature clapper 41 are constant throughout the frequency spectrum of mechanical vibrations encountered in present day mobile and non-mobile installations.

A further feature of this invention is that any motion of the armature clapper 41 causes a flow of electric currents in the armature itself. These currents are familiarly known as eddy currents. These currents ow in such a direction that a magnetic field is produced by them which opposes the armature motion. The phenomena becomes more pronounced as the frequency of vibration increases. This damping due to the tlow of the said eddy currents can be enhanced by coating the surface of the armature 14 adjacent to the magnet with a highly conductive metal (such as silver). Fig. 4 shows a magnet design in which this feature of eddy current damping is further emphasized. A highly conductive metallio vane 53 (which may be made of silver) is rigidly mounted to the armature -clapper 41 and positioned between the poles of a strong permanent magnet. The permanent magnet 54 is designed so that almost all of its useful flux passes through the vane 53. Any motion of the vane 53 in this field produces eddy currents which impede the free movement of the armature 41 as heretofore described.

Fig. 3 illustrates the mounting of the magnet 48. The poles rof the magnet fit the bracket holes 50 and 51 of the bracket 49. The magnet carrying bracket 49 is positioned on the plate 22 so that the shank portion of the two of the studs 25 extend through the bracket. The staking of the studs fixes the position of the magnet.

What is claimed is:

1. In an electromagnetic relay of the type having a core and an armature, the combination of a relatively high conductivity metal disposed on the armature on the opposite side thereof from the core and a permanent maignet mounted adjacent to the relatively high conductivity metal to generate eddy currents in the high conductivity metal by movement of the armature.

2. In an electromagnetic relay of the type having a core and an armature, the combination of highly con ductive plating on the surface of the armature on the opposite side thereof from the core and a permanent magnet having a pole `face adjacent to the plated surface of the armature to generate eddy currents in the conductive plating by movement of the armature.

3. In an electromagnetic relay of the type having a Icore and an armature, the combination of a high conductivity metallic vane secured to and projecting from the armature `on the opposite side thereof from the core and a permanent magnet assembly having 1a pair of spaced apart pole pieces between which the metallic vane projects to generate eddy currents in the metallic vane by movement of the armature. p

References Cited in the le of this patent UNITED STATES PATENTS 1,987,144 Dinkel Ian. 8, 1935 

